From EP 1 229 985 B1, such a filter device is known which concerns preferably an oil filter for cleaning lubrication oil, in particular for internal combustion engines of motor vehicles. The known filter device comprises a filter housing for receiving a filter element, wherein the filter housing has an inlet on the crude side and an outlet on the pure side. In the inserted state, the filter element separates a crude chamber that communicates with the inlet from a pure chamber that communicates with the outlet. Furthermore, the filter housing of the known filter device has a drain line which communicates with the crude chamber and which forms a plug receptacle for an axially and eccentrically projecting plug which is formed on the filter housing, into which receptacle the plug is plugged in the inserted state of the filter element. Thus, the plug closes the drain line when the filter element is properly inserted into the filter housing. For a simplified finding and inserting of the plug into said plug receptacle, in the known filter device, a concentrically arranged and helically ascending or descending ramp is provided at the housing, wherein the plug receptacle, thus an inlet region of the drain line, is arranged between a lower ramp end and an upper ramp end. When screwing on a cover, together with which the filter element is inserted or screwed-in, through the rotation of the filter element and through the sliding of the plug along the ramp, the plug automatically finds the plug receptacle, can penetrate therein and close the drain line. In a particularly advantageous embodiment of the known filter device, the ramp and the plug can interact according to the key-lock-principle so that only a filter element provided with a plug adapted to the ramp can be used in such a manner with the housing of the known filter device that the plug finds and closes the plug receptacle automatically when screwing-on the cover.
With a missing filter element or when using a filter element which is not specifically adapted to the filter housing, a sufficient purification of the respective liquid for the operation of the internal combustion engine can not be ensured. Accordingly, the danger of damage to the internal combustion engine caused by contamination carried along with the respective liquid increases.